Radius indicator



Oct. 14, 1958 J. SVOBODA RADIUS INDICATOR 3 Sheets-Sheet 1 Filed Dec. 2'7, 1955 $35 41 02?.103 m35 m EOOm EDJDQZmm DM ZOW INVENJOR. JAMES svoBopA BY I ATTY.

Oct. 14, 1958 J. SVOBODA 2,855,835

RADIUS INDICATOR Filed Dec. 27, 1955 I :5 Sheets-Sheet 2 JNVENTOR. JAMES SVOBODA ATTY.

Oct. 14, 1958 J. SVCYJBODA RADIUS INDICATOR Filed Dec. 27, 1955 3 Sheets-Sheet 3 FIG. .3

INVENTOR. JAMES SVOBODA @MW ATTYQ United States Patent 'Ofiice 2,855,886 Patented Oct. 14, r1958.

2,855,886 RADIUS INDICATOR James'Svoboda, Bridgman, Mich, assigmor to Clark Equipment Company, a corporation of Michigan Application December 27, 1955, Serial No. 555,397 12 Claims. (Cl. 116124) This invention relates to an indicating device,.. and more particularly to a radius indicator for cranes and the like. v

In the operation of hoisting apparatus, and particularly cranes of various types, a platform, or tractor suitably supports a control cab and an adjustable boom. The boom is fitted at its outer end with load receiving means or tackle which is controlled frornthe cab. A vertically swinging boom has attached to it boom rigging, whereby the vertical inclination of the boom may be adjusted. Such a boom may be constructed of a built-up structure of. selectively varying length, and the effective length thereof'may be varied by adjusting the boom angle of elevation and/or by varying the length of the built-up boom structure.

' It is well known that the maximum load carryingcapacity (if a crane or boom depends upon theoverhanging length thereof, which in vertically swinging cranes varies with the angle of inclination of the boom to the horizontal. This length is known as the working radius, which is the vertically projected boom length plus afixed length between the pivot point of the boom and the center line of rotation. On a crane having a vertically swinging boom of any given length, the vertically projected boom length or the measured horizontal distance between the boom pivot and the plum line of the load will be hereinafter referred to as the boom radius. It will thus be evident that the boom radius will represent the base of a triangle, that the length of the boom will represent the hypotenuse of the triangle, and that the remaining side thereofis represented by the plum line of the load. The angle between the base and the hypotenuse will, of course, vary as the boom is elevated. At the same time the base line, which represents the boom radius, will vary in length. The maximum weight carrying capacity of the machine will vary,'with any given length of boom, as afunction of boom radius.

Various types of boom radius indicating devices have been heretofore devised, but no such indicator has been previously devised which is both simple in construction and which allows a crane operator to instantly perceive the boom radius from a single calibrated scale having equal increments of division thereon, irrespective of variations in the vertical inclination of the boom or in the length thereof.

It is a primary object of this invention to provide visual boom radii indicating means by the'use of which an operator can instantly perceive the boom radius of a crane and the like irrespective of variations in boom length or elevation.

Another object of this invention is to provide a boom radius indicator which is low in cost, easy to manufacture,'and relatively simple in structure.

A further'object of this invention is to provide a boom radius indicator of the type specified having a single evenly calibrated pendulum scale on which the boom radius is continuously indicated by means which varies inlength in proportion to variations in boom length.

It is another object of this invention to provide a boom radius indicator having means associated therewith for maintaining an element thereof in a continuously vertical position during operation of the boom.

Qthe r objects and advantages of thisvinvention'will become apparent to persons skilled'inthe art following areading of the detailed description which follows.

indicator shown in Figure 1;

In carrying out my invention I employ a free swinging pendulum devicehaving an equally: calibrated. scale.

marked thereon for indicating boom radius, whichtscale is operatively connected to a boom length proportioning member, which is rigidly connected to the boom in per-- pendicular relation thereto, by means varyingin length. in proportion to boom length, one end of the length varyingmeans being movable along the scale of the pendulum 1 device during variations in. elevationof the boom for. indicatingboomradius thereon. Y 1 j p In the accompanying drawingsx-f .f

Figure 1 is a side elevation of a crane machine embodying my invention and showing infdottedlines thezeifect of a variation in boom elevation on boom radius;

Figure 2 is an enlarged front elevation of the radius.

Figure 3 is a side view of Figure 2 in Figure 4 isageometricdiagram illustrating the principle of operation of my device. 1 j p Referring now to the drawings and first to Figure 1, aswing body 10 of a portable crane is connected to a traction support 12 in a well known manner, and a boom 14 of well known construction is pivotally connected at 16;, to the front end of bodylll; a winch driven cable 18.is. connected to the outer end of the boom for causing pivotal movement thereof about pivot16. .;.A, hoisting cable 20 is trained overapulley 22 andfis 'adapt'edfto engage and move a loadfsuch' as 24.. A. boom radius indicating means 30 is suitably mounted on the boom 14 for. 'indi-I eating the radius of the boom 14. at all-times.

Referring now to Figures 2 and;3,:the.radius indicator 30 includes a free'swinging rectangular pendulum mem ber 32 having a weighted lower end 34, azcentrally located. longitudinally extending slot 36, asimila'rly slottedp erh partial section;

. dulum reinforcing member 38 rigidlyconnecte'd .tofthd member 90 in predeterminedspaced relation, eachbeih back 'of the pendulum,;a cylindrical locking member 40; having an opening 42-therethroughfor receivingarotab' able shaft 44, and aset screw 46 extending through a slot 48 in member40 for fixing the position thereof on: shaft 44. A boom radius scale 50 extends longitudinally of the pendulum adjacent the slot '36 and, as shown, is. divided into equally scaled five-foot increments from five to forty feet, inclusive. j

The ends of ahollow cylindrical drum 60'a'rejco vered by flat circular end plates 62 and 64 which are connected, i as by welding, to longitudinally extending members of boom 14. A plate member is-boltedto the top sectionof drum 60 and is removable for permitting entry thereto; The shaft 44'is mounted in drum 60 in coaxial relation therewith, being revolvable in an annular bushing 72 which is mounted in a ring-shaped retaining'mernber 74 bolted to plate 64. The drum 60 is preferably filled to a" predetermined level, as shown, with a' high density liquid for a purpose to be described. A; hollow'fioat member a 76 is fixedly connected tothe shaft 44 at one sidelthe'reof by bolts '78 whichextend into a horizontally projecting v section 80 of the float.-

a Q Q I Located on a step down portion ofshaft 44 adjacent the outer face of plate .62'is 'a ball be'aring'SZ on which is mounted a non-revolvable,cup-shaped cylindrical mem-E.

ber 84 which is connectedto,platetizflby a plura ity of circumferentiallylocated bolts 86; a cylindrical projection 88 extends outwardlyffrom the creme 'of member' 841',

Loosely mounted on member 88is,a generally 'dow wardly extending elongated plate 90 whichis rigidly con nected to boom member 68 by welded plate members... 92 and'94 and: ,a bolt 96 in such a. manner that jtheff longitudinal axis of member 90- isflfixedly.disp'osed, at. right angles ,to the; longitudinal. axis of the .boom'11 4. 'A} plurality of "openings=100"are'locate.d. along fthej .axi

adapted to receive one end of a link of predetermined length which operatively connects a selected opening in member 90 with slot 36 of pendulum 32. Each of said openings is locateda distance from the axis of shaft 44 which is directly proportion'altofl a particular maximum boom radius, the numeral markings adjacent the various openingsbeing representative of a plurality of maximum boom radii which correspond to a plurality of boom lengths. It will be understood that when a boom of any length is horizontal the working radius is greater than the boom radius bya constant dlstancewhi'ch is equal to the distance between the center line of rotation and the boom pivot; For example, a link 104. is' of such predetermined lengththat when the upper end there'- of is inserted through the opening 100 which is r'narkcd 25, the opposite'or lower end thereof, which extends through and is held in slot 36 by a washer 105, will,for.

example, be' immediately adjacent the 275 foot marking on the scale of pendulum 32 when the boom 14 is lowered to a horizontal position and the working radius is 2.5 feet greater than the boom radius; Likewise, asecond link 106 is of such predetermined length that the lower" ly accommodate widely varying boom lengths which may have a range of maximum boom radii, for example, which increase in five foot increments between a minimum twenty-five feet and a maximum seventy feet, as indi cated on the scale of member 90. The length of pendulum 32 and the length of the slot 36 and the scale 50 may, of course, be varied as desired to accommodate the maximum variation in boom length which may be utilized with a given crane.

Referring now to Figure 4, the geometric relation of the various parts of the radius indicator and of a boom of various lengths is indicated in line diagram. In the diagram, AF represents a relatively short boom, and AG a relatively long boom, each of which booms is represented as being pivotally connected to a crane machine at point A. The radius of boom AF at the indicated angle (90-x) is AH, and the radius of boom AG is AI. The boom radius of each of said booms will, of course, vary' from maximum to minimum as the angle (90 x) between. the boom and radius lines varies from minimum to maximum, respectively. If the boom radius line were scaled and radius indicating tracer bars a and b, equal in length to one-half the length of booms AF and AG, respectively, were hung from the mid-points of booms AF and AG, respectively, it is-apparent jthatthe boom radius of each boom would be continuously indicatedon the scaled boom radius line by each of the tracer bars. For example, point H will move along the boom radius line horizontally under end point F of boom AF and toward point A as boom AF is elevated from the position shown toward a vertical position, the boom radius being continuously indicated by the end point of tracer aas it moves toward point A. Tracer bar b will likewise continuously indicate the boom radius of boom AG as theelevation thereof is varied.

radius lines, whereas line ED is illustrative of the scaled member 90 which is in fixed right angle relation to the boom, thereby forming a right triangle BCD with the pendulum and radius lines. It will now be apparent that triangle BCD is always geometrically similar to triangle ACB irrespective of the angle of elevation of the boom; i. e., each angle of triangle ACE is always equal to the corresponding angle of triangle BCD, one angle I have taken advantage of this principle of radius indiof each of said triangles being always a right angle, a second angle of each of said triangles being always equal to x, and the third angle of each of said triangles being always equal to (-x), as illustrated. It will also be apparent that the same triangular similarity exists"be,

tween triangle BCD and any other triangle formed between a vertical line and the boom and radius lines', such as triangles AFH or AGI.

In this arrangement the length of line ED is proportional to the length of any given boom, line BC is proportional to the radius of any such boom at any angle of elevation thereof, and line CD is proportional to the vertical distance between the end of any such boom and the radius line thereof. Lines d and e are represented as fixed at pre-selected points along the line BD' tion is increased and decreased, respectively, so as to indicate the boom radius on line BC for each of two different lengths of boom in the same manner that simulated tracer bars a andb indicate the boom radii along line'AHI for the boom lengths AF and AG, respectively. These lines d and e, of course, represent link bars such as 104 and 106, respectively, which are connectable between pendulum scale 36 and the proper boom length openings in member 90. Y

By this arrangement a single pendulum scale calibrated,

in equal increments may be utilized as a boom radius indicator for any length of boom within the limits of the scale when combined, as shown in Figures 2 and 3, with a maximum boom radii scale 90, positioned as described,

and a set of links of proper lengths for connecting scale} 90 to the pendulum.

My radius indicator maybe constructed by selecting;

a pendulum 32 of anyrdesired length, and calibrating the slot 36 thereof in equal increments of division up to any desired preselected maximum working radius marking. The marking at the pivot shaft 44 shall read equal to the distance between the center line of rotation and the boom pivot pin or zero if these two points should be one and the same. An elongated member 90 is next hung vertically from the pivot of pendulum 32 so that its longitudinal axis is parallel to the axis of the pendulum. Openings are then located by marking each on member 90 at a distance from pivot shaft 44 which is equal to one-halfthe distance from said pivot shaft to the corresponding working radius marking on pendulum 32. Connecting links (or a suitably marked telescoping link). are then selected which are of lengths equal to the aforementioned distances between openings 100 and pivot shaft 44.

When the radius indicator parts are then mounted as shown in Figure 2, wherein each connecting link is equal in length to the distance of the corresponding opening 100 from pivot shaft 44, the working radius of the boom is continuously indicated on scale 36 as fully discussed above.

The liquid charged drum 60 and the weight 34 are utilized as aids for maintaining pendulum 32 in a vertical position at all times, irrespective of variations in the elevation of the boom; e. g., the pull or push of a connecting link on the pendulum 32 with variations in boom elevation is always countencted by the weight 34 and by the force of buoyancy which the liquid in drum 60 exerts on float 76. Float 76 acts through lever arm member 80 and shaft 44 to counteract the force imposed on the. pendulum by a connecting link duringoperation of the boom. Obviously, either the Weight 34 or liquid charged drum 62 and associated structure may be used singly to produce the desired eifect, or other equivalent means may be used to insure that pendulum 32 remains in a vertical position at all times during operation of the boom, such verticality being essential to the proper operation of my radius indicator.

From the above it will be apparent that irrespective of the boom length in use, a crane operator can readily perceive the working radius at which he intends to lift any given load, and by consulting a load capacity chart in the cab of the crane machine will instantly know the lifting capacity of such machine at any given radius, the above being accomplished simply by connecting the proper opening of scale member 90 to the slot 36 of the pendulum by a link of proper length. The equally spaced scale markings on the pendulum greatly simplifies visual perception of same over prior known radius indicators.

Although I have illustrated and described but one embodiment of my invention it will be apparent to persons skilled in the art that certain changes in construction and the arrangement of parts may be made without departing from the scope of my invention as defined in the claims appended hereto.

I claim:

1. In combination, a boom, a swingable member opoperatively connected to said boom having evenly spaced scale markings thereon, means connected to said member for maintaining verticality thereof irrespective of variations in elevation of the boom, means mounted in perpendicular relation to the longitudinal axis of said boom and means connected to said mounted means and to said swingable member in such a manner that the boom radius is continuously indicated by said latter connecting means on the scale markings of said swingable member during operation of the boom.

2. In combination, a boom, pendulum means operatively connected to said boom and swingable relative thereto during elevation thereof, boom radius indicating means on said pendulum means, means mounted in fixed perpendicular relation to the longitudinal axis of said boom, said pendulum means and said mounted means being interrelated in such a way that the angle therebetween is always equal to the angle between the longitudinal axis of the boom and the boom radius line, and means connecting the mounted means to the pendulum means for indicating the boom radius on said radius indicating means.

3. The combination claimed in claim 1 wherein said latter connecting means comprises an elongated member which is connected to said mounted means at a predetermined position between the ends theerof, said position being located a distance from one end of said mounted member which is proportional to the boom length, and the efiective length of the said elongated member bein equal to the said distance.

4. A working radius indicator for booms of varying length comprising first means swingable from the boom for continuously maintaining a vertical position, second means mounted in fixed predetermined relation to the longitudinal axis of the boom, and third means linking said first and second means, said third means being pivotally connected to the said second means and movable vertically on said first means, said first, second and third means being so interrelated that a triangle is formed thereby which is continuously similar to an imaginary triangle formed by the longitudinal axis of the boom, 8. 76

. 6 boom radius line, and a boom radius tracer line connecting said boom axis and boom radius lines.

5. A radius indicator as claimed in claim 4 wherein .said first means comprises a pendulum having boom radius indicia thereon and mounted at one end thereof in pivoted relation to the boom.

6. A radius indicator as claimed in claim 5 wherein said second means comprises an elongated member mounted in perpendicular relation to the boom and having boom length indicia thereon.

7. A radius indicator as claimed in claim 6 wherein the indicia on said second means is scaled to vary in proportion to boom length, the indicia on said first means is scaled in equal increments of boom radii, and the said third means comprises a member of predetermined length proportional to boom length for operatively connecting the indicia of said first and second means in a manner such that the boom radius is continuously indicated by said member on the indicia of said pendulum during operation of the boom.

8. A working radius indicator for booms of varying length and elevation comprising liquid charged means mountable on a boom, rotatable means mounted in said liquid charged means, elongated boom radius indicia means fixed to said rotatable means, and float means in said liquid charged means operatively connected to said rotatable means for maintaining said elongated means in a vertical position irrespective of variations in the elevation of the boom.

9. A working radius indicator for booms of variable length and elevation comprising a liquid charged container mounted on said boom, a rotatable shaft mounted in said container, float means operatively connecting the liquid in said container to said shaft, a pendulum fixed to one end of said shaft having equal spaced indicia means thereon and an elongated slot formed therein adjacent said indicia means, said pendulum being adapted to rotate with said shaft during elevation of the boom to maintain a vertical position, an elongated member having boom length indicia thereon and mounted in fixed perpendicular relation to the longitudinal axis of the boom, the axis of which member forms an angle with the axis of the pendulum which is continuously equal to the angle of .boom elevation, and means of variable length for connecting the boom length indicia of said elongated means to the slot in said pendulum, whereby elevation of the boom effects increasing angularity between the pendulum and said elongated means and further eifects movement of said connecting means in a boom radius decreasing direction along the indicia of said pendulum.

10. A working radius indicator for booms comprising scaled pendulum means arranged to be hung from the boom, scale means arranged to be mounted in fixed right angle relation to the boom axis and forming a variable angle with said pendulum means, and link means pivotally connected to the scale means and having a portion movable vertically on said pendulum for indicating the radius in cooperation with the scale on the pendulum.

11. A radius indicator as claimed in claim 10 wherein the pendulum means is scaled in terms of working radius, the scale means is scaled in terms of boom length, and the link means is of a length which is equal to the distance between a boom length scale marking on the scale means and the apex of said variable angle.

12. A radius indicator as claimed in claim 10 wherein the pendulum means is sealed in terms of working radius, the scale means is scaled in terms of boom length, and

the link means is of a length greater than one-half the distance between the apex of said variable angle and a corresponding working radius marking on said pendulum means.

References Cited in the file of this patent FOREIGN PATENTS 420,921 Great Britain Dec. 11, 1934 

